The purpose of this randomized, clinical study was to evaluate the clinical performance of composite resin materials used for fillings and indirect inlays. Twenty-eight sets of five class II restorations (two fillings, three inlays) were placed in 88 premolars and 52 molars in 28 adults. Brilliant Dentin and Estilux Posterior were used for both fillings and inlays, and SR-Isosit for inlays only. After 11 years, 27 sets of restorations (96%) were evaluated clinically using modified United States Public Health Service criteria. Replaced or repaired restorations were observed in 16% of the fillings and 17% of the inlays, and a further 5% of the restorations were replaced for reasons not related to the restoration. The remaining 107 restorations exhibited optimal ratings in 30% of the fillings and 12% of the inlays (P<0.05) and acceptable ratings in 70% and 88%, respectively. The reasons for failure were fracture of restoration (four fillings, five inlays), secondary caries (two fillings, four inlays), fracture of tooth (two inlays), loss of proximal contact (two fillings), and loss of restoration (one inlay). Failures were seen more frequently in molar than premolar restorations (P<0.05), with no significant difference between fillings and inlays or between the five types of restoration (P>0.05).